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5. Technical description
5.1. Functional description
5.1.1. Product functions
5.1.1.1. Protection functions
Table 5.1.1.1.-1 IEC symbols and IEEE device numbers
Function description IEC symbol IEEE Device No.
Three-phase thermal overload
protection
θ> 49M
Motor start-up supervision
based on thermal stress
calculation
I
s
2
t
s
48/14
Three-phase definite-time
overcurrent protection, low-
set element
I
s
> 51/14
Three-phase instantaneous or
definite-time short circuit
protection, high-set element
I>> 50/51
Inverse-time unbalance
protection based on negative-
phase-sequence current
I
2
>46
Phase reversal protection REV 46R
Definite-time undercurrent
(loss of load) protection
I< 37
Instantaneous or definite-time
ground-fault protection
I
0
> 50N/51N
Cumulative start-up time
counter and restart disable
function
∑t
si
66
Circuit-breaker failure
protection
CBFP 62BF
Temperature protection using
RTD sensors or thermistors
ThA>, ThB> 49/38
Lockout relay 86
For protection function descriptions, refer to Section 5.1.4.13. Technical data on
protection functions.
5.1.1.2. Inputs
The relay is provided with four energizing inputs, two digital inputs and three
optional digital inputs controlled by an external voltage. Three of the energizing
inputs are for the ground-fault current.
Motor Protection Relay
Technical Reference Manual - ANSI Version
REM 610REM 610
1MRS755537
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